1. Field of the Invention
The present invention relates to a nonflammable polyester resin composition and a method for manufacturing such a polyester resin composition. The present invention also relates to a reusing technique for mold processed products of thermoplastic resins to be disposed as wastes.
2. Description of Related Art
At present, thermoplastic resins, such as polyester resins and polycarbonate resins, and resin compositions thereof have been used in a wide variety of fields as molding materials for products, such as containers, packing films, household articles, office apparatuses, AV apparatuses, electric and electronic parts, automobile parts and the like, because of superior moldability, mechanical properties, heat resistance, weather resistance, outside appearance, sanitary properties and economical efficiency hereof. For this reason, the used amount of mold-processed products of the thermoplastic resins or the resin compositions thereof is very large, and at present, the used amount has also been increased year by year. On the other hand, the amount of spent mold-processed products to be disposed as wastes has also been greatly increased, resulting in serious social problems.
Under these circumstances, in recent years, container and package recycling law and laws (normally, referred to as Green Purchase Laws) relating to promotion of providing environmental products by the Nation or the like have been successively enforced, and public concerns have been focused on material recycles of mold processed products of such thermoplastic resins or the resin compositions thereof. Among these, the establishment of a material recycling technology for PET bottles, made from polyethylene terephthalate (hereinafter, sometimes referred to as PET), whose amount of use has rapidly increased, has become an urgent task. Moreover, along with the wide use of optical recording medium products (optical discs) made from polycarbonate (hereinafter, sometimes referred to as PC), such as CD's, CD-R's, DVD's and MD's, researches have been carried out on a reusing method for waste ends generated upon mold-processing these products and a reuse of transparent PC materials obtained after separating reflecting layers, recording layers and the like from waste optical discs.
However, these mold-processed products of polyester resins such as spent PET bottles, and polycarbonate resins such as optical discs, collected from the market, are inmost cases deteriorated due to hydrolysis and thermal decomposition and the like. For example, when an attempt is made to again mold pulverized materials derived from these mold-processed products, no molding process can be performed due to an extreme reduction in melt-viscosity, or, even if a molded product is obtained, the resulting product is poor in mechanical strength and easily broken, with the result that, at present, it is very difficult to reuse these to provide molded products at a level sufficient for practical use.
As a method for collecting recycle-use resins from waste mold-processed products, for example, a method is proposed in which an ethylene copolymer containing an epoxy group is melt-kneaded in pulverized pieces of mold-processed products of thermoplastic resins, such as PET and PC, or the resin compositions of these (Japanese Patent Application Laid-Open No. Hei 5-247328, Japanese Patent Application Laid-Open No. Hei 6-298991 and the like), or another method is proposed in which an epoxidized diene-based copolymer is melt-kneaded therein (Japanese Patent Application Laid-Open No. Hei 8-245756). Moreover, Japanese Patent Application Laid-Open No. 2003-183486, Japanese Patent Application Laid-Open No. 2003-213112, Japanese Patent Application Laid-Open No. 2003-221498, and Japanese Patent Application Laid-Open No. 2003-231796 have proposed a material technique in which a rubbery polymer is combined with R-PET (recycled PET) so as to improve the impact strength thereof. However, these known techniques use a nonflammable agent containing halogen atoms so as to obtain a high fire-preventive performance, and the addition of the nonflammable agent containing halogen atoms fails to sufficiently improve the impact strength. In the case when the added amount of the nonflammable agent containing halogen atoms is reduced, an insufficient nonflammable performance tends to occur. As a result of these, it is not possible to expand the application. Moreover, the nonflammable agent containing halogen atoms causes a problem of safety against the environment and human bodies due to the halogen atoms contained therein.
In view of the above state of the art, the present inventors and the like made various investigations concerning a recycling method that is practically usable for pulverized materials derived from PET bottles that are typical collected materials made from polyester resins, and based upon the resulting findings, further made investigations concerning a method for utilizing pulverized materials derived from optical discs made from polycarbonate resins. As a result, they have found that a resin composition, obtained through processes in which a polymer mixture containing predetermined (A) to (E) components is subjected to a predetermined space-passing process in its melted state, has superior mechanical performances, and is allowed to exert a self-extinguishing characteristic in the air. It has been found that these effects can be obtained not only by the use of pulverized materials of PET bottles and pulverized materials of PC optical discs, but also by the use of normal virgin PET and PC, and the present invention is thus completed.
An objective of the present invention is to provide a nonflammable polyester resin composition that has a superior nonflammable property, in particular, a self-extinguishing property, without the necessity of containing a halogen-atom-containing nonflammable agent, and also has superior mechanical performances, such as sufficient elastic modulus, bending strength and impact strength, and a method for manufacturing such a resin composition.
Another objective of the present invention is to provide a nonflammable polyester resin composition which, even in the case when polyester resins and/or polycarbonate resins obtained from waste mold-processed products to be disposed are reutilized, exerts a superior nonflammable property, in particular, a self-extinguishing property, without the necessity of containing a halogen-atom-containing nonflammable agent, and also has improved mechanical performances, such as sufficient elastic modulus, bending strength and impact strength, and a method for manufacturing such a resin composition.